NAJAF, Iraq --An angry crowd gathered in the streets of the holy city of Najaf as funerals were held for three bodyguards killed in a bomb attack outside the home of one of Iraq's top clerics.

At least 2,000 Shiite Muslims followed behind the wooden coffins, with many of them carrying posters of Ayatollah Mohammed Saeed al-Hakim who was slightly wounded in the neck in Sunday's bombing.

Some blamed supporters of rival Shiite leader Moqtada al Sadr for the attack at a Shiite spiritual center about 161 kilometers (100 miles) south of Baghdad. (Full story)

Sadr has criticized the U.S. occupation of Iraq and refused to join the coalition-backed Governing Council.

"This was Moqtada al Sadr. His people did it,'' 60-year-old Muslim Radii, told Reuters. "Now there will be revenge. The only way to stop this is for the people of Najaf to stop it. We will have to form our own militia.''

Sadr's group has denied responsibility for the bombing.

Supreme Council for the Islamic Revolution in Iraq (SCIRI), one of the country's main Shiite groups, said it was the target of the attack, Reuters reported.

Hakim is the uncle of SCIRI leader Ayatollah Mohammed Baqer al-Hakim.

The blast killed two guards outside the building and a worker inside the office and 10 people -- mostly pedestrians -- were wounded, one seriously, a spokesman for the ayatollah told CNN.

Hakim, who has had contact with U.S. officials since before the U.S.-led war in Iraq, was walking through a hallway when the blast went off and received minor injuries from glass shards, his spokesman said.

The spokesman said an explosive device had detonated inside a gas canister that had been left outside an office where the ayatollah's son was working.

The home is about half a mile south of the Imam Ali Mosque, a site sacred to Shiites around the world. Ali was the son-in-law of the prophet Muhammad and the first leader of the Shiite community.

The spokesman also said that the ayatollah and his followers hold the U.S. military responsible for maintaining security in Najaf and therefore hold the Americans indirectly responsible for the attack.

Iraqi police said Hakim apparently received a death threat last week, but did not report it to police.

The spokesman confirmed the death threat, and said the ayatollah and other leading Iraqi religious figures in Najaf had received threats telling them that they must leave Najaf or be killed.

Meanwhile in Beirut, the Shiite Muslim guerrilla group Hizbollah -- which is on a U.S. list of "terrorist'' groups -- condemned the bomb attack as a "very serious development," Reuters reported.

"This incident must be met with harsh condemnation from all religious scholars and the community. And a strong message must be sent to these criminals and whoever is behind them,'' Hizbollah leader Sheikh Hassan Nasrallah said in a statement.